The present invention relates generally to power generation equipment such as fuel cells, and particularly to thermal management of fuel cells, for example, solid oxide fuel cells.
A fuel cell is an energy conversion device that produces electricity by electrochemically combining a fuel and an oxidant across an ionic conducting layer. A high temperature fuel cell bundle, for example, a solid oxide fuel cell bundle is typically constructed from flat single members having a planar configuration. The planar fuel cells can be of counter-flow, cross-flow and parallel flow varieties. The planar fuel cell typically comprises tri-layer anode/electrolyte/cathode components that conduct current from cell to cell and provide channels for gas flow into a cubic structure or stack.
Fuel cells, such as solid oxide fuel cells, have demonstrated potential for high efficiency and low pollution in power generation. However, problems associated with thermal management persist, particularly in regulating the temperature gradient of the fuel cell components. Thermal energy generated in the fuel cell from the reaction of the fuel and the oxidant needs to be removed or used internally in order to maintain the operating temperature in the fuel cell. Cooling channels in the fuel cells typically use an oxidant, such as air, to aid in the transfer or removal of waste heat from the fuel cell to the oxidant, so as to maintain a stack temperature at or below prescribed limits and maintain a predetermined thermal gradient. A temperature difference between a fuel cell assembly and a fluid, such as the oxidant, is a function of heat transfer characteristics of the fluid flowing through the fluid flow channel and a heat flux generated in the fuel cell assembly. However, such fluid flow channels, as used in conventional fuel cell applications, have a low convective thermal transfer coefficient between the fluid flow channel and the fluid flowing therethrough. Accordingly, there is a need in the art for a fuel cell having improved fluid passages that provide improved heat transfer characteristics.